Issue 55

D.-h. Zhang et alii, Frattura ed Integrità Strutturale, 55 (2021) 316-326; DOI: 10.3221/IGF-ESIS.55.24

Figure 12: Cyclic stress/strain curves of solder layer TIM2

acc 

W acc

Figure 13: Accumulated creep strain and creep dissipation energy density distribution in solder join per cycle

Theoretical model

Predicted results

Relative error (%)

Engelmaier model

325

18.6

Creep strain model

274

17.0

Creep strain energy density model

330

Table 3: The predicted fatigue life of the TIM2 layer in SiC-IGBT power module .

C ONCLUSION

I

n this paper, the finite element thermomechanical model of SiC-IGBT power module was established, and the cyclical stress-strain distribution and creep behavior of the Sn3Ag0.5Cu solder layers was obtained under -55 o C~175 o C cyclic ambient temperature loading. Consequently, according to the obtained range of shear strain, accumulated creep strain and creep strain energy density at the corner point of the solder layer, the corresponding thermal fatigue lives were determined by Engelmaier model, creep strain model and creep strain energy density model, respectively. The comparisons of the predicted lives indicate that the thermal fatigue lives predicted are in an acceptable agreement. The proposed constitutive model of Sn3Ag0.5Cu solder and the FE-based thermal fatigue evaluation for the SIC-IGBT power module is feasible.

A CKNOWLEDGMENT

T

he research work was supported by the National Natural Science Foundation of China (No. 11972376), the National Natural Science Foundation of Shandong Province (No. ZR201910250083) and the Fundamental Research Funds for the Central Universities of China (No.20CX02308A).

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